My reasearch started with Mikes video:
Actually in the video the best groups are made with conical. (there are three videos)
Then, in his video he uses 456-220 gr bullet, (as opposed to 450-200), which makes me ask this question. And revolver is not Pietta (like mine)
I am also considering the safey - for chain fire, the difference between 456 and 450.
So any experience is most welcome.
One more thing, as a comment from my European side: I noticed that most Americans will use powder loads in range from 25 to almost 30 grain.
(My guess due to tradition, and prefference to stronger loads)
But, my own experience with ball, 454 cal is following:
I started gradually reducing the loads from 24 gr, down to 21 - 18 and finally 15.
So far, the 15 grain load makes the best groups for my revolver. 25 meters, groups of 5 inches.
So once when I establish which caliber for conical bullet to use (456 or 450) I will make tests at range for accuracy by reducing the load.
BTW, the manual of my gun states that recomnded loads are 12 to 15 grains, and max 30 grains. My guess is: 12 to 15 for target shooting, 30 for hunting. Wahtever the reason, the accuracy in my experience is improved by reducing the load.
My intention now is to get conical and make tests.